Make module autoload warnings configurable (#2763)
Make module autoload warnings configurable (#2763)

Modules generated by the module creation machinery currently print out
a notice that warnts the user that things are being autoloaded.  In
some situations those warnings are problematic.  See #2754 for
discussion.

This is a first cut at optionally disabling the warning messages:

- adds a helper tothe EnvModule base class that encapsulates the
  config file variable;
- adds a method to the base class that provides a default (empty)
  code fragment for generating a warning message;
- passes the warning fragment into the bit that formats the autoload
  string;
- adds specialized autload_warner() methods in the tcl and lmod
  subclasses;; and finally
- touches up the autoload_format strings in the specialized classes.
mfherbst/spack,mfherbst/spack,lgarren/spack,TheTimmy/spack,LLNL/spack,LLNL/spack,skosukhin/spack,matthiasdiener/spack,iulian787/spack,lgarren/spack,krafczyk/spack,matthiasdiener/spack,krafczyk/spack,skosukhin/spack,LLNL/spack,TheTimmy/spack,matthiasdiener/spack,iulian787/spack,skosukhin/spack,lgarren/spack,LLNL/spack,TheTimmy/spack,iulian787/spack,tmerrick1/spack,EmreAtes/spack,iulian787/spack,iulian787/spack,tmerrick1/spack,skosukhin/spack,mfherbst/spack,krafczyk/spack,lgarren/spack,mfherbst/spack,EmreAtes/spack,matthiasdiener/spack,skosukhin/spack,krafczyk/spack,tmerrick1/spack,TheTimmy/spack,EmreAtes/spack,tmerrick1/spack,EmreAtes/spack,mfherbst/spack,lgarren/spack,TheTimmy/spack,LLNL/spack,EmreAtes/spack,krafczyk/spack,matthiasdiener/spack,tmerrick1/spack